Conveying mechanism for furnaces



Oct. 18, 1932. w. M. HEPBURN 1,883,788

CONVEYING MECHANISM FOR FURNACES Filed sept. e, 1930 2 sheets-sheet 1 gjm/vento u El' WILL MMM. HEPBURN nh um N.

Oct. 1.8, 1932. w. M. HEPBURN 1,883,788

CONVEYING 'MEGHANISM FOR FURNACES y Filed Sept. 6, 1930 2 Sheets-Sheet 2 Patented ct. llS, E932 i STATES -PA'rErrr oFFicE y WILLIAM M. HEPBURN, OF TOLEDO, OHIO, ASSIGNOR TO SURFACE OOMBUSTION CORPORA- TION, OF TOLEDO, OHIO, A CORPORATION OF NEW YORK CONVEYING MECHANISM FOR FURNACES Application led September 6, 1930. Serial No. 480,082.

This invention relates to improvements in conveying mechanism for moving Work such as steel sheets through a heat treating furnace and more particularly through a furnace having a heating chamber and a cooling chamber through which latter chamber the Work must pass after leaving the heating chamber. Furnaces of this type, that is, furnaces having a heating chamber and a cooling chamber are known as normalizing furnaces, the steel sheets to be heat treated or normalized being brought up to temperature in the heating chamber and then passed into the cooling chamber for cooling at a controlled rate.

The usual type ofnormalizing furnace has v a roller hearth, made up of a series of discs mounted ongindividual shafts which extend transversely of the furnace. Aside from being an expensive construction, it has been found in actual practice that so-called Wasters7 or foundation sheetsmust be interposed between the roller hearth and the steel sheets to be normalized in order to prevent scratching of the surface of the sheets. Endless convcyers have also been proposed but are impractical primarily for the reason that they carry a tremendous amount of heat out of the furnace. The present invention has for an object to provide, in combination with a furnace having a heating chamber and a cooling chamber, a conveyer of such form and construction in the heating chamber that there shall be practically no heatlosses from the heating chamber by reason of the conveyer carrying heat out of the heating chamber and to provide in the cooling chamber a conveyer Which tends to carry heat out of the cooling chamber.

In accordance With this phase of the inven-` tion, the conveyer iny the heating chamber consists of reciprocal members for moving the Work longitudinally of the heating cham-4 ber in vafseries of hops or steps, the conveying` mechanism being of such form and construction that the provision of special openings in the furnace arch, side Walls or floor thereof, for the accommodation of the conveyer mechanism, shall be unnecessary, the only openings being the usual openings at the opposite ends of the furnace through Which the Work is introducedinto and discharged from the furnace, the conveying mechanism in the cooling chamber comprising an endless conveyer the upper flight of which forms in effect a continuation of the conveying mechanism in the heating chamber. The conveying mechanism in the heating chamber is of such form and construction that the Work is lifted from and redeposited on its supporting bed Without relative longitudinal movement With respect to said bed, in order to prevent `scratching of the sheets due to sliding friction between the sheets and the conveying mechanism. The endless conveyer in the heating chamber is adapted to be held stationary While the sheets are being deposited thereon from the reciprocating conveyer, in order to prevent sliding friction between the endless conveyer and the sheets, the conveyer after the sheets have been deposited thereon being actuated to move the sheets through the cooling chamber, either continuously or with an intermittent motion as may be desired.

Another object of the invention is to provide improvements in the reciprocating or so-called Walkingbeam conveyer which is used for carrying the Work through the heating chamber.

The various features of novelty and invention will more fully appear from the detailed description taken in connection with the accompanying drawings forming part of this specification.

Referring to the drawings:

Fig. lis a longitudinal side elevation of the improved conveying mechanism showing how the same'is combined with a furnace having a heating chamber and a cooling chamber, the

furnace being in longitudinal vertical section;

Fig. 2 is a fragmentary plan View of the adjacent ends of the two types of conveying mechanism, the view being taken on line 2 2 of Fi 1 and being enlarged as compared with ig. 1;

Fi 3 is a section taken on line 3 3 of Fig. 4 of t e preferred form of mechanism for actuating the walking beam conveyer, the view also showing a portion of the front end of the heating chamber; j

Fig. 4 is a vtransverse section on line 4 4 of Fig. 3;

Fig. 5 is a vertical section through a detail of the operating mechanism, the view being taken on line 5 5 of Fig. 4;

Fig. 6 is a transverse section on line 6 6 of Fig. 9;

Fig. 7 is a cross section on line 7 7 of Fig. 9; f

Fig. 8 is a perspective view of one of the arms making up the link mechanism shown in Fig. 7;

Fig. 9 is a fragmentary side elevation of the link connection between the reciprocating members of the walkin beam mechanism;

Fig. 10 is a cross section taken on line 10 1() of Fig. 9;

v Fig. 11 is a vertical section on line 11-11 of Fig. 2, and

Fig. 12 is a diagram showing'the cycle pf v movement of the work-moving member of the a combustion chamber 20 into which one or more burners 21 discharge, the hot gases from the burner flowing forwardly towards the work ingress end 16 and being deflected downwardly upon the work by reason of the slope of the roof 15. 22 indicates a series of burners positioned in the side walls of the heating chamber beneath the level of the work ingress opening for supplying hot gases beneath the work.

' Depending from the forwardly projecting wall 19 which forms the bottom of the combustion chamber 20, is a wall 23 which is continued rearwardly as at 24 to form the restricted passage T leading into. the cooling chamber C. The cooling chamber is preferably a metallic structure the roof 25 being shown as corrugated. The cooling chamber i at the work egress end is preferably of restricted form as indicated at 26 to provide a slot-like egress for the work. A door 28 may be provided at the exit end of the coolin chamber anda door 29 is preferably provide at the ingress end of the heating chamber. The floor of the furnace is indicated at 30 and is substantially at the same level in both the heating and cooling chambers. The furnace itself forms no part of the present invention except as the same may be in combination with the conveying mechanism next to be described. f f

. The conveying mechanism in the heating chamber is generally indicated at 31, and the conveying mechanism in the cooling chamber at 32. The conveying mechanism* 32 in the cooling` chamber is an endless conveyor, the upper flight of which rests on asole plate 33, suitably supported ontransversely extending piers 34 which rise from the floor 30 in the cooling chamber. This conveyer preferably comprises a series of endless chains 35 each of which being preferably supported on its own sole plate 33. Extending transversely of the furnace below the bridge wall 24 is a shaft 36 on which are mounted sprocket wheels 37 about which the chain belts 35 are.

looped, it being noted that the shaft 36 is located adjacent the entrance to the restricted passage T from the heating chamber H and adjacent the discharge end of the conveyor 31 within the heating chamber. The other end of the endless conveyor 32 is looped over -sprocket 38 on a shaft 39, suitably supported outside of the cooling chamber C, the lower flight of the conveyor returning into the so'v cooling chamber through a suitable opening 40 in the end wall 41 thereof, the piers 34 being apertured as indicated at 42 to permit the passage of the conveyer as will be readily understood. V Y

As will be noted from Fig. 2, provision of individual sole plates 33 for the individual chains forming the upper, flight of the conveyer allows substantially unrestricted circulation of the cooling gases both above and below the conveyor. The gases in the cooling chamber are gases which flow thereinto through the restricted throat or passage T from the heatin chamber and consequently a neutral or reducing atmosphere may be maintained within the cooling chamber the same as is maintained within the heating chamber. There is no stack for the exit of spent gases of combustion from the furnace and consequently there will exist in the heating chamber as well as in the coolingchamber a pressure slightly above atmosphere tending to prevent the free entry of air into the furnace, the spent gases finding exit through thev work ingress and egress openings. L

The conveying mechanism within the heating chamber for introducing the sheets or work thereinto will next be described. Rising from the floor 30 of the heating chamber is a plurality of longitudinally and transversely extending piers generally indicated3 .shaft 36 to a point outside of the furnace at the front end thereof. The rails 48 are preferably -of I-form in cross section and formed of a heat-resisting alloy as are also the stools 46. It is not necessary to pro.

vide anti-friction means between the rails 48 and their supporting stools since sliding friction between the rails and stools results in a hard smooth surface when the `parts are at high temperature.

Mounted above the rails 48 are individual rails 49 both being held from lateral displacement by the upstanding side walls 47 on the stools 46. Supported on the individual rails 48 are a series of links 50 which in turn support the rails 49, the upper and lower rails being maintained in such relation that the links 50 are normally disposed a-t an oblique angle with respect to said rails'48 and 49, the inclination being such that the upper rails-are maintained under longitudinal tension in the direction of movement of work into the heating chamber.v

The links 50 are preferably of wedgefshape form at their opposite ends in order to provide a knife-edge-type bearing between the rails. The preferred construction of the links is shown in Figs. 7' and 8. As clearly shown in these views, each link comprises a pairof side arms 51 provided at one end with an angular extension 52 which is wedge shaped in cross section to provide a knifeedge-type bearing as indicated at 53. Projecting from the angular extension 53 is a lug 54 adapted to enter and project through an aperture 55 in the opposite end of the other link and to be upset as clearly indicated in Fig. 7 whereby the two arms make up a unitary structure. It will be noted that both arms are duplicates of one another, the angular extension of'one arm contacting with one rail and the angular extension of the other arm contacting with the other rail.

The rail 49, like the rail 48, is preferably of I-form in cross section. Where angular extensions 52 of the links 50 project through the webs of the rails, the webs are thickened as indicated at'56 in Fig. 10 to compensate for cutting away of the side flanges of the rails between the links. It will be seen that the rails 48 and 49 are coupled by the links 50 in a manner to prevent separation of the rails. This is a feature of great practical importance since the upper and lower rails and links can be assembled as a unit before being placed in the stools 46. Also the construction permits ready removal oft theinterlocked rails from the stools as will be readily understood. ln order to confine the ends of the links 50 to their seats on the rails, the latter are provided with projections 57 as clearly shown in Fig. 9. These projections may consist of parts welded to the rails.

From the foregoing description it will be seen that by holding the upper rails 49 stationary and moving the lower rails 49 longitudinally, the upper rails 49 will be raised or lowered as the case may be, depending upon the direction of movement of the lower rails 49. The means for causing relative movements between the rails 48 and 49 and also for causing simultaneous movement thereof will be later described.

The work to be conveyed through the furnace is indicated at W. The work while not being conveyed by the reciprocating mechanism 31 rests on a laterally discontinuous bed generally indicated at 58, which bed is co-extensive with the work moving rails 49. This bed is made up of a series of rails 59 shown in Fig. 11 as individually supported on the stools 46 laterally of thel other rails 48 and 49.v The bed rails 59 like the other rails 48 and 49 are of heat resisting alloy and are preferably of I-form in cross section. However, Where the rails 59 are supported on the stools 46, the lower flange may be cut away as indicated in Fig. 11 in order to permit the use of a slot for holding the rails in place. The upper level of the bed 58 is, of course, above the lowermost level of the work-moving rails 49 in order to permit the rails 49 to be retracted without moving the work resting on the bed 58. While it is preferred to mount the rails 59 in the manner indicated nevertheless, it will be readily appreciated that other means may be resorted to as regards the functioning or mode of, operation of the movable rails 48 and 49.

As clearly indicated in Fig. l1, the bed rails 59 and the upper movable rails 49 may be provided with a surface of refractory material 61 of suitable composition to prevent or to reduce pitting of the sheets resting thereon: pitting of the sheets as distinguished from scratching being caused by hard particles of oxide becoming attached to the metal when metal conveyers are used and consequently by providing a suitable refractory surface .on the sheet supporting members the tendency of pitting of the sheets is materially reduced or entirelyprevented.

The mechanism for independently reciprocating the rails 49, and for moving the rails 48 and 49 in unison will next be described. Referring more particularly to Figs. 3 and 4, reference numeral 62 indicates laterally spaced tracks shown as of channel form, these tracks resting on a suitable foundation 63. 64 indicates generally a carriage adapted to 'spect to the carriage 64.

ride on the rails 62. This carriage is la rectangular frame the sides 66 of which are shown as of I-form in cross section and the ends 67 of which are shown as channel irons. This carriage is supported on wheels 68 for running on the tracks 62, the wheels being shown as secured to the ends of individual shafts 69 which are supported by individual brackets 70 secured to the side beams 66 of the carriage. Extending longitudinally of the carriage along opposite sides thereof and secured to the underside of the side brackets 70 are racks 71, these racks being positioned inwardly of the tracks 62. 72 indicates idler gears, one for each rack 71, these idlers being supported on stub shafts 73 suitably secured to the sides ofthe respective tracks 62` The idlers 72 are driven in unison by individual pinions 74 secured on a common driving shaft 75, the ends of the shaft being supported in a bowl-like fixture 76 adapted to contain a lubricant and secured to the underside of the tracks 62. This shaft is driven by any suitable prime mover, preferably an electric motor as indicated at 77 in Fig. 4.

The work-engaging rails 49 are anchored to the carriage 64 by a flexible connection Iserving to prevent relative longitudinal movement vbetween said carriage and rails but permitting relative vertical movement therebetween. To this end the adjacent ends of the rails 49 are fiXedly secured to a cross beam 78 to which is pivoted a horizontally disposed link 79 which at its other end is pivoted to a pedestal 80 iixedly secured to the carriage 64, a pair of such pedestals and links being provided, one at either side of the carriage.

Supported on the carriage 64 is another carriage generally indicated at 81.` This carriage 81 is a rectangular frame the longitudinally extending sides 82 of which are shown as of I-form cross section as are also the transversely extending connecting beams 83. This carriage 81 is not only of sufficiently less width than the carriage 64 in order to be positioned therein but is considerably shorter in length in order to permitndependent longitudinal travel of the carriage 81 with re- The carriage 81 is provided with wheels 84 which ride on the side rails 66 of the carriage 64, these wheels being mounted at the ends of individual shafts 85 which are mounted in brackets 86 secured to the upper side of the side beams 82 of the carriage 81. Mounted on the individual shafts 85 are links 87 which extend at the same incline as the links 50, the upper ends being pivoted to brackets 89 secured to cross beams 89 which e'Xtend transversely below the rails 49 to support the same. These links 87 are of the same effective length as the links 50, previously described.

The longitudinally reciprocable rails 48 have adjacent outer ends secured to the carriage 81 ina manner to prevent the relative longitudinal movement between the carriage 81 and the rails 48. To this end thereis mounted on the carriage 81 one or more pedestals 90 for supporting a transversely eX- tending beam 91 to which the adjacent ends of the rails 48 are fiXedly secured. The connection between the beam 91 and the pedestal 90 may be such as to permit relative vertical movementin order to'prevent binding between the carriage and the rails 48.

F rom the foregoing description it will be readily appreciated that the work-lifting rails 49 may beelevated and lowered with respect to the fixed bed 58 by causing relative longitudinal movement between the rails 48 and 49 and that after such relative movement has been accomplished, the rails 48 and 49 may be moved in unison Without relative longitudinal -movement therebetween by moving the carriage 64. The cycle of movement of the rails 49 is such as to describe a rectangular path as shown in Fig. 12. In other words, the work is lifted vertically by the rails 49 from the bed 58 and then moved longitudinally of the bed a distance determined by the longitudinal movement of the carriage 64, the rails 49 then being lowered to redeposit the Work on the bed 58 and the rails 49 then retracted to their original position.

The mechanism for causing longitudinal movement of the carriage 81 which supports the rails 48 can be of any suitable form. As shown in the drawings this mechanism comprises a screw 92 anchored at one end to a transverselyv extending beam 83 of the carriage 81, the shaft being held against rotation. The shaft is moved longitudinally by a worm gear 93 through which the screw shaft passes, the worm gear being rotated by a worm 94 connected by suitable shafting to a prime mover 95 shown as an electric motor. 96 indicates the mounting for the parts 92, 93 and 94. Two devices 96 as shown, one on either side of the motor 95, these devices as well as the motor 95 being mounted on a suitable platform 97 supported by the carriage 64, the platform being shown as secured to the side beams 66 of the carriage 64 by brackets 98.

The motor 95 for actuating the carriage 81 and the motor 77 for actuating the carriage 64 may be interconnected by suitable circuits and controlling mechanism in such a manner that the carriage 64 will not be moved until after the carriage 81 has completed its travel. It willalso be appreciated that the length of stroke of the carriage 64 can be varied to suit the required speed of travel of the Work or sheets into and through the heating chamber.

`The endless conveyer 32 may be drivenrin any suitable manner as by an electric motor generally indicated at 99, which motor may be so controlled that the conveyer 32 will not be actuated while work is being deposited thereon from the reciprocating conveyer 31. It will also be appreciated that the conveyer 32 can be controlled as to speed and consequently that the rate of movement of the work through the cooling chamber may be controlled as conditions may warrant From the foregoing description it will be readily appreciated that the present invention provides not only an improved type of so-called walking beam conveyer for moving the work in a series of hops or steps, but also provides a novel combination of conveying means for a-` furnace having a heating chamber and a cooling chamber. The endless conveyer 32 in the cooling chamber carries heat out of the cooling chamber but this is not an -undesirable feature. On the contrary this is a desirable feature since it is desired that heat be abstracted from the cooling chamber. While the invention `has been described in considerable detail more pparticularly as relates to the reciprocating conveyer mechanism, nevertheless it will be understood that other types of walking beam conveyers may be utilized for carrying work into the heating chamber without departing from the.

spirit of the invention.

What is claimed is A l. In apparat-us for conveying work in a series of steps, the combination of a-series of laterally spaced rails, means for supporting said rails, said rails being longitudinally but not verticall reciprocable', a complemental series of wor -engaging rails disposed above the other rails., a work-supporting bed above the level of the first mentioned rails and through the plane of which bed the work-engaging rails are movable, a series of links supported on each lower rail and supporting the rail thereabove in parallel relation with respect to the lower rail, the links extending *obliquely longitudinally of the rails when the upper of said rails is below the level of said bed, means rigidly coupling the adjacent ends of one set of said rails, means rigidly coupling the adjacent endsef the second set of said rails, means for moving the lower set ,of rails-longitudinally independently of the upper set o f rails to raise and lowerthe upper set of rails, and means for moving both sets of rails in unison following independent movement of the lower set of rails.

2. In apparatus forcoiveying work in a series of steps, the combination of a longitudinally extending support, a rail supported on and reciprocable longitudinally but not vertically wit-h respect to said support, a work-supporting bed above said rail, a work-engaging rail extending longitudinally above said railv and- A adapted to be moved above and below the plane of said bed and longitudinally thereof, a series of links supported on the lower rail and. directly supporting the upper rail in parallelism therewith, all ofthe links extending in the same direction, means independent of said links for moving the lower rail independently of the upper rail to raise and lower the upper rail above and below the plane of said bed, and means for moving said rails in unison following the raising and lowering of the upper rail.

3. In apparatus for conveying work in a series of steps, the combination of a longitudinally extending support, a rail supported on and reciprocable longitudinally but not vertically@ with respect to said support, a work-supporting bed above said rail, a workengaging rail extending longitudinally above said rail and adapted to be moved above and below the plane of said bed and longitudinally thereof, a series of links supported on the lower rail and directly supporting the upper rail in parallelism therewith, the links extending obliquely longitudinally of said rails when the upper rail is below the plane of said bed, means for moving the lower rail independently of the Vupper rail toraise and lower the upper rail above and below the plane of said bed and means for moving said rails in unison following the raising and lowering of the upper rail, the opposlte'endsof each link being of wedge shape to provide knife-edge-type bearings and being anchored to the rails to tie the rails to ether.

4. In apparatus for conveying wor in a series of steps, the combination of a longitudinally extending support, a rail supported on and reciprocable longitudinally but not vertically with respect to said support, a work-supporting bed above said rail, a workengaging rail extending longitudinally above said rail and adapted to be moved above and below the plane of said bed and longitudinally thereof, a series of links supported on the lower rail and directly supporting the upper rail in parallelism therewith, the links extending obliquely longitudinally of said rails when the upper rail is below the plane of said bed, means for moving the lower rail independently of the upper rail to raise and lower the upper rail above and below the lane of said `bed and means for moving sai rails in unison follow-l ing the raising and lowering of the upper rail, said links each comprising complemental side arms each having an angular extension at one end of wedge shape formto provide a knife-edge-type bearing at each end of the link, the angular extension of one arm extending through one of said rails and the angular extension of the other arm extendin throu h the otherrail whereby to tie the rai s toget er.

5. In apparatus for conveying work in a series of steps, the combination of a longitudinally extending support, a rail supported on and reciprocable longitudinally but Vnot vertically with respect to said. support, a

work-supporting bed above said rail, a workengaging rail extending longitudinally above` said rail and adapted to be moved above andv below the plane of said bed and longitudinally thereof, a series of links supported on the lower rail and directly supporting the upper rail in parallelism therewith, the links extending obliquely longitudinally ofy said rails when the upper rail is below the plane of said bed, means for moving the lower rail independently of the upper rail to raise and lower the upper rail above and below the plane of Said bed andmeans for moving said rails in unison following the raising Iand lowering of the upper rail, said links each comprising complemental side arms each havlng an angular extension at one end, the

langular extension of one arm extending tudinally extending support, a rail supported on and reciprocable longitudinally but not vertically with respect to said support, a work-supporting bed above said rail, a work- Y engaging rail extending longitudinally above said rail and adapted to be moved above and below the plane of said bed and longitudinally thereof, a series of links supported on the lower rail and directly supporting the upper rail in parallelism therewith, the links extending obliquely longitudinally of said rails when the upper rail is below the plane of said bed, means for moving the lower rail independently of the upper rail to raise and lower the upper rail above and below the plane of said bed and means for moving said rails 1n unison following the raising and lowering of the upper rail, said links having angular extensions extending through the rails for tying the rails together.

7..' In apparatus for conveying work in a series of hops or steps, the combination of a longitudinally extending support, a rail supported on and reciprocable longitudinally but not vertically with respect to said support, a series of links supported on said rail, a work-engaging rail supported on said links, said rails being of I-form in cross sect-ion, said links each comprising complemental side arms each having an angular extension at i one end, the angular extension of one arm extending through one of said rails and the angular extension of the other arm extending through the other of said rails, the adjacent ends of the arms being secured together, the

' arms being positioned on opposite sides of the vertical web of said rails.

8. ln combination, a furnace having a heat.v

r reciprocable conveyer for moving thework Lesage@ in a series of hops or steps through the heating chamber, a coo-ling chamber forming a continuation of said heating chamber, and

an endless conveyer the upper flight of which from each other by a restricted passage, a

vertically and horizontally reciprocable conveyer for moving the work longitudinally of the heating chamber in a series of hops or steps and terminating adjacent the restricted passage and an endless conveyer extending from adjacent the discharge end of said reciprocable conveyer and through the cooling chamber for carrying through the cooling chamber the work discharged from the re ciprocable conveyer.

l0. ylhe combination with a furnace rhaving a heating chamber wherein the work is brought up to temperature and a cooling chamber wherethrough the work must pass after leaving the heating chamber, said chambers being separated from eachother by a restricted passage, of a laterally discontinuous work-supporting bed within the heating chamber, a laterally discontinuous workengaging member adapted to be moved above and below the plane of said bed and longitudinally thereof for conveying the work longitudinally of said bed in a seriesl of hops or steps, said member terminating adjacent said restricted passage, and an endless conveyer forming .a continuation of said bed through said restricted passage and cooling chamber and adapted to receive the work as it leaves the heating chamber.

ll. ln conveying apparatus for a furnace, the combination of a laterally spaced set of rails extending out of the furnace through an end thereof, means below the individual rails for supporting them for longitudinal but not vertical movement, a second set of similarly spaced rails above'the first set of rails, links extending directly from the rails of the lower set to the rails of the upper set for supporting the latter, means for moving both sets of rails longitudinally in unison, and means for moving said sets longitudinally with respect to each other whereby to raise and lower the upper set of rails, said supporting means for the lower setof rails being above the floor of the furnaceand comprising channelled members for preventing lateral displacement of said rails.

12. In conveying apparatus for a furnace, the combination of a laterally spaced set of rails extending out of the furnace through an end thereof, means below the individual rails for supporting them for longitudinal but not vertical movement., a second set of similarly spaced rails above the first set of rails, links extending directly from the rails of the lower set to the rails ofthe upper set for supporting the latter, means for moving botli sets of rails longitudinally in unison, and means for moving said sets longitudinally with respect to each other whereby to raise andv lower the upper set of rails, said supporting means for the lower set of rails comprising longitudinally spaced chaiinelled member between the side walls of which the upper rails are movable.

13. In combination, a furnace chamber, laterally-spaced pairs of upper and lower rails within said chamber, means between the rails of each pair for movably supportingr the upper rail in parallelism with the lower rail, longitudinally discontinuous channels wherein each pair of rails is confined against lateral displacement, said channels being formed in stools disposed above the floor of said chamber, means independent of said means and outside of said chamber at one end thereof for reciprocating said pairs of ra ils in unison and for reciprocatingthe rails of each pair with respect to each other to raise and lower the upper rails, and means supported on said stools for supporting work when the upper rails are lowered as aforesaid.

14. In a conveyor for intermittently moving the work forwardly vin a furnace, the coin,- bination of a work-lifting mechanism ccmprising upper and lower rails extending in parallel relation, links extending .directly from one rail to the other for maintaining them in parallel relation, said links each comprising two side members each having an angled extension to which the non-angled end of the other member is secured, a portion of each rail being confined between said side members.

15. In a conveyor for intermittently moving the work forwardly in a furn ace, the combination of a work-lifting mechanism comprising upper and lower rails extending in parallel relation, links extending directly combination of a laterally spaced pair of upper and lower rails within said chamber and projecting therefrom, means between and individual to each pair of rails for supporting the upper rail on the lower rail and for moving the upper rail in a vertical plane when relative longitudinal movement is imparted to said rails, means below the lower rails for supporting them for longitudinal movement, means coupled to the outer end of the lower rails for moving them in unison independently of the upper rails, means for supporting the outer end of the upper rails for vertical movement, and means coupled to the last-V 18. In combination, a furnace chamber wherein articles may be heated in passing therethrough, two relatively movable beds in said chamber for alternately supporting said articles, one of said beds comprising laterally spaced pairs of rails extending in parallelism one above the other, means independent of the upper rails for slidably suport-ing the lower rails, links individual to each pair of rails for rockably supporting the upper rail on the lower rail, and means for reciprocating the lower rails to raise and lower the upper rails.

19. In combination, a furnace chamber wherein articles may be heated in passing therethrough, two relatively movable beds in said chamber and projecting therefrom for alternately supporting said articles, one of said beds comprising laterally spaced pairs of rails extending in parallelism one above the other, links individual to each pair of rails for rockably supporting the upper rail on the lower rails, means-in said chamber for slidably supporting the lower rails, and means coupled to the projecting end of the lower rails for reciprocating the latter to raise and lower the upper rails.

In testimony whereof I affix my signature.

WILLIAMl M. HEPBURN.

from one rail to the other for maintaining them in parallel relation, said links each comprising two si de members each having an angled extension to which the non-angled end of the other member is secured, said angled extensions being'of wedge shape to provide linev type bearings on the rails. A

16. In a conveyor for intermitently moving the work forwardly in a furnace, the combination of a work-lifting mechanism comprising upper and lower rails of T-form in cross section and extending in parallel relation, links extending directly from one rail to the other for maintaining them in parallel relation, said links having wedge shape terminals to form line type bearings on the rails, the links compri sing side members between which a web portion of each rail is confined.

17. In a conveyor for intermittently moving work forwardly in a furnace chamber, the 

